fix: address account valuation review findings

jarca_ledger_mcp/infrastructure/sqlite/__init__.py

@@ -1,6 +1,9 @@
 from .connection import DEFAULT_DB_PATH as DEFAULT_DB_PATH
 from .connection import connect as connect
+from .connection import connect_readonly as connect_readonly
 from .connection import db as db
+from .connection import read_db as read_db
+from .connection import DatabaseNotInitializedError as DatabaseNotInitializedError
 from .connection import resolve_db_path as resolve_db_path
 from .migrations import init_db as init_db
 from .migrations import migrate_db as migrate_db
@@ -16,7 +19,10 @@ __all__ = [
     "SCHEMA_VERSION",
     "TRANSACTION_ADDITIVE_COLUMNS",
     "connect",
+    "connect_readonly",
     "db",
+    "read_db",
+    "DatabaseNotInitializedError",
     "init_db",
     "migrate_db",
     "resolve_db_path",